The screens in computers used in public places, such as in ticket vending machines, are usually touchscreens. Selections are typically made using a finger as a pointing means. Such screens are large, so the buttons and other elements to be activated can also readily be large enough. Furthermore, applications often enable selections to be easily made between only a few alternatives, and usually no text, for example, needs to be entered either.
Touchscreens are often utilized in portable PDA (Personal Digital Assistant) devices that are becoming increasingly popular. Since most functions can also be implemented through keys modelled on a screen, a touchscreen substantially reduces the number of necessary mechanical keys. Consequently, such devices become smaller. Since the aim is to make the portable PDA devices as small as possible, the touchscreens used therein are also small. Furthermore, the functions of the applications in the devices are more versatile, and a screen can be provided with many elements to be selected. For example, the buttons of a qwerty keyboard can be modelled on a touchscreen in order to enable text to be entered. Since the screen is small and several elements to be selected are simultaneously displayed on the screen, the elements are substantially small. In addition to the modelled keys, another frequently used input mechanism is handwriting recognition. Thus, on account of the small keys and handwriting recognition, a touchscreen is often used by means of a small writing device, i.e. a stylus, such as a small pen-shaped object.
On many occasions it would be desirable to use a PDA device with one hand only. This is a problem when a touchscreen requires a stylus to be used as the pointing means. Using a stylus typically necessitates two hands; one for holding the device and the other for using the stylus to point at a desired point. It can be inconvenient and too time-consuming to extract a stylus from its storage slot in order to execute minor functions. Sometimes the small stylus may also be lost. In these situations, the user often eventually uses his or her finger as the pointing means. When the elements to be indicated are very small, e.g. on the touchscreens of the PDA devices, the surface area of a fingertip is, however, rather large with respect to these elements. A finger is an extremely inaccurate pointing means since it completely covers a target to be selected and important information around the target as well. In such a case, the user cannot be sure as to which elements he or she is pointing at.
In connection with large touchscreens, a solution is known wherein a user is able to determine the location of a pointer where the location of the pointer and the contact on the screen differ from each other (Offset). This solution enables the pointer to be removed from directly under the finger such that the user can more easily see what the pointer is currently pointing at. In the solution, the user is not shown in advance how the pointing means actually works. The user, according to a common practice, assumes that the cursor moves to the contact point since the user is not informed about the offset already setup in the device. The pointer moves to a different point than assumed and desired by the user, and this makes the device slower to use, or may result in pointing and selecting incorrect targets. Even after the user has realized how the pointing works, he or she must bear the extent of the offset in mind in order to be able to operate the device smoothly.